IN THIS APPENDIX
Most of the time, when you learn a new language, you start with simple data types—numbers, strings, and so on. Only after you learn how to declare simple variables, and maybe even write a few
if/for/while statements, do you venture into the world of objects. If you want to learn Java, however, you need to learn how to create a Java class right away.
You can’t write a Java program without creating a class. A class is a grouping of data items and code. A class definition may consist of only code, only data items, or both. ...